Packet position detecting system



July 14, 1959 c. E. MULDERS ET AL 2,894,626

PACKET POSITION DETECTING SYSTEM 2 Sheets-Sheet 1 Filed April 12, 1956 INVENTORS c. E. MULDERS & B. VISSER ATT'Y July 14, 1959 c. E. MULDERS ET AL 2,894,626

PACKET POSITION DETECTING SYSTEM Filed April 12, 1956 2 Sheets-Sheet 2 F|6.2A/ I STAMP a CAHCELLING C. E. MULDERS & B. VISSER ATT'Y United States Patent F PACKET POSITION DETECTING SYSTEM Cornelis 'Emilius Mulders, The Hague, and Bertus Visser, 'Rotterdam, Netherlands, assignors t0 Staatsbedrijf der Posterijen Telegraphic en Telefonie, The Hague, Netherlands Application April 12, 1956, Serial No. 577,848 Claims. (Cl. 209-111) This invention-relates to a packet position detecting system. More partieularlyit deals with such a system for photoelectrically determining in which position a packet is oriented by detecting the location of a predetermined phosphorescently marked portion on the packet, such as a phosphorescent postage stamp on a letter, which system may be employed for controlling a sorting or letter facing machine.

Previously, photoelectric responsive systems have been employed for detecting the position of stamps on letters, such as that shown in the Roddy US. Patent No. 1,729,- 521 in which the photoelectric devices respond to the difference between the light reflected from the postage stamp and from the letter surface. However, in view of the great differences in colors between stamps and surfaces of letters this system is not always accurate and may be easily affected by light reflected into the photoelectric devices from external sources.

It has also been proposed to provide special type of stamps containing a metallic material, such as a metal foil, which may be detected magnetically, but such devices are also inaccurate in that they respond to any metal parts in the letters themselves, such as paper clips, staples and the like. Furthermore such special stamps containing a metal foil are expensive.

Diflerent fluorescent code markings at predetermined positions on letters which are only visible when irradiated with invisible light, have been used and detected photoelectrically for indicating the destination of a letter, such as that disclosed in Doust US. Patent No. 2,609,928, but such photoelectric devices are easily influenced by extraneous light at the time the markings are irradiated and accordingly also give rise to inaccuracies in this system.

This application is a continuation in part of the Mulders and Visser copending application Serial No. 335,744 filed February 9, 1953, and now abandoned.

It is an object of the present invention to produce a system for detecting the position of similarly shaped and sized packets, such as letters, in a simple, efficient, effective, economic, accurate and rapid manner.

Another object is to produce such a system having photoelectric devices that are not affected by extraneous light sources.

Another object is to produce a system for detecting the position of a stamp on an envelope regardless of the color of the stmp or of the envelope, and for operating a conventional sorting or letter facing machine.

Another object is to produce a postage stamp having phosphorescent properties for detection in a system of the type disclosed in this invention.

Generally speaking, the system of this invention comprises the method of detecting the position of each of a plurality similar packets, each packet having a special mark thereon in a predetermined location, comprising: successively passing the packets past two spaced stations along a path, one of which stations radiates the special marked portion on each packet to produce an afterglow therefrom and the other station detecting the exact loca- Patented July 14, 1959 ice 2 tion of said afterglow while being shielded from ex traneo-us light sources. The packet then may be sorted, oriented or faced in accordance with the detection made at said other station, such as facing letters for stamp cancelling and/ or post marking.

An important prerequisite for the operation of the system of this invention comprises the special marking on the packet whose position is to be detected. This marking must have special luminescent properties, namely of phosphorescence, in which once the portion having the marking is illuminated by a special light, such as an ultraviolet light from a mercury vapor lamp, it will retain its luminescence and continue to glow for a reasonable period of time, say for example at least 50 milliseconds, after it has been irradiated, so that the radiation will continue until the packet is moved to another station. In the case of postal packets or letters, the phosphorescent marking material may be incorporated in the postage stamps when they are printed or before they are sold to the consignors of the packets or letters, and thus the phosphorescent marking material may be controlled by the issuer of the stamps, namely the government, so that the machine or device of this invention maybe made to correspond and be selective to the particular phosphorescent material which is employed on the stamps.

A specific apparatus which may be employed in detecting the phosphorescent stamps may comprise a movable carrier or conveyor for the postal packets on which the packets are successively moved past two spaced stations, the first of which may be provided with an ultraviolet light or lights for illuminating all sides of the packet upon which the stamp may occur, and the second station which may be shielded from all outside light, such as by a tunnel through which the packets are successively passed, and in the sides of which tunnel may be located separate photoelectn'c detecting devices at each possible position for a stamped or marked portion to appear on a packet. Since postal letters have only two sides and the stamp is generally placed in the upper right hand corner of one side of each letter, there are only four different positions which a regular row of letters could take along the conveyor, and accordingly, only four different photoelectric detecting devices are required for detecting the afterglow of the stamps irradiated at the first station, namely one position up and one position down on each side of the tunnel. The specific photoelectric devices may have their outputs amplified for controlling relays, which relays may be employed for operating gates or switches along the path of the conveyor after the second station, to switch the packets into their proper orienting devices for alignment before entering a stamp cancelling, post marking and/or destination dispatching machine.

The above mentioned and other features and objects of this invention and the manner of attaining them are given more specific disclostn'e in the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

Figure 1 is a schematic perspective view of a detecting apparatus according to this invention adapted for detecting the position of postal letters by detecting the location of stamps thereon;

Figs. 2a and 2b are schematic wiring diagrams of one form of photoelectric circuits which may be employed for the lower and upper pairs of detecting devices in connection with the apparatus shown in Fig. 1; and

Fig. 2c is a schematic structural and wiring diagram of one form of a letter facing apparatus which may be controlled by the circuits in Figs. 2a and 2b.

Referring specifically to Fig. 1, one specific example of the system of this invention is disclosed for the detection of positions of stamps on postal letters in which the letters are placed on a conveyor belt 1 in channel 1 and passed in the direction of the arrow through separate spaced operating stations I and II along said conveyor belt 1. It is preferable that the packets being scanned by this invention have substantially all the same size and shape and be placed in an even row on the conveyor belt 1 so that the position of the packets may be more accurately determined by the device. There are shown on the conveyor 1 in front of the station I four letters 2, 3, 4 and 5, each in a different one of the four possible positions for the letters along the conveyor 1. Those letters shown which have stamps shown in dotted lines their address on front side away from the side viewed in Fig. 1 so that letters 2 and 3 have their stamps adjacent their bottom edge along the conveyor ll, letter 2 with its address side facing the observer and letter 3 with its back toward the observer; and letters 4 and 5 have their stamps adjacent the upper edge of each letter, letter 4 with its address side facing the observer, and letter 5 with its back toward the observer.

As each of the letters passes station I, ultraviolet radiation sources 6 and 7, such as mercury vapor lamps, irradiate the letters 5, 4, 3, 2 successively, including the phosphorescent material in their stamps, which material will continue to glow or radiate energy after it has passed station I and into the second station II.

The second station II preferably is herein shielded from the ultraviolet radiation source 6 and 7 as well as from other outside light sources by a tunnel 8 which may be provided with lower and upper apertures or openings 9 and it respectively, on both sides of the tunnel 8, which apertures are covered by or with the corresponding four separate photoelectric afterglow detecting devices. These apertures 9 and 16 in the tunnel is may have any arbitrary shape and the photoelectric devices mounted over them may be adjusted to be responsive to at least a predetermined voltage impulse when a phosphorescent or glowing stamp is moved adjacently past them.

As shown in Figs. 2a and 21; these photoelectric devices may comprise separate photoelectric cells 9, 9", 10' and 10 corresponding, respectively, to the opposite lower apertures 9 and opposite upper apertures These photoelectric cells 9, 9", it) and It?" may be separately connected, respectively, to amplifier electron tubes 11, 12, 13 and 14, the former or lower two of which may be connected to operate a relay A and the latter or upper two of which may be connected to operate a relay B, so that relay A is operated by the detection of postal packets in the positions of packets 2 and 3 and relay B is operated by the detection of postal packets in the positions of packets 4 and 5. These relays A and B may be employed for directly operating any mechanical gating or sorting device well known in the art, or separate relays may be connected to each of the amplifier tubes 11, 12, 13 and 14 for controlling separate gate magnets as shown in Fig. 22 of Hopp U.S. Patent No. 1,217,092. In Fig, 2c herein these relays A and B are shown operating their corresponding switches a and b in other circuits of a letter facing machine containing solenoids I5 and 17, respectively, to move a gate 16, either into its full line position or into its dotted line position shown.

Thus, according to Fig. 20, if letter or packet 2 or 3 passes station II, photocell 9 or 9" receives phosphorescent light from the stamp and amplifier 11 or 12 becomes conductive to operate the relay A to close its corre sponding contacts a and energize the solenoid or electromagnet 15 to pull the ate 16 into its full line posi tion shown in Fig. 2, so that letter 2 or 3 may pass directly from station Ii by conveyor belt 1 through a channel 13, gate 16 and channels 19 and 29 to a stamp cancelling machine (not shown), which machine may comprise a stamp cancelling device 22 and 23 on each side of the channel 20, one for each letter 2 and 3, respectively.

If on the other hand the letter or packet is in the position of packet or letter 4 or 5, then photoelectric cell 1G or It)" will receive phosphorescent light from its stamp, and amplifier 13 or 14 will become conductive to energize relay B to operate its corresponding contacts b and energize the electromagnet 17 for pulling the gate 16 into the dotted line position shown in Fig. 2. This then conducts the postal packet 4 or 5 from the channel 18 through gate 16 and channel 24 to a turn-over device 25 (which may be similar to that shown in Maitland co-pending application Serial No. 311,253 assigned to the same assignee as this application). This turn-over device 25 may comprise a crossed belt by means of which the packet 4 or 5 is turned around its longitudinal horizontal axis before being discharged through a channel 26 which may join the channel 20 leading to the stamp cancelling machines 22 and 23.

If four separate facing operations are desired an additional facing machine may be connected in series with the machine shown in Fig. 26 for turning the letters again into another position so that they will be exactly in the same position. In such a system one of the four photoelectric detecting devices may be eliminated, because letters or packets in one of these four different positions need no turning and therefore no detecting because at least one of these four positions could be a normal position for letters entering the stamp cancelling machine.

Although the system of this invention is directed specifically to a device for controlling a facing machine for postal packets such as letters, it is obvious that the principle of this invention may be employed for detecting the positions of any plurality of similarly shaped and sized packets which may have in the same predetermined location thereon a particular phosphorescent marking which may be irradiated and then its afterglow detected for determining the position of the packet, and t .en also therefrom control the operation of a sorting machine.

While there is described above the principles of this invention in connection with specific apparatus, it is to be clearly understood that this description is made only by way of example and not as a limitation to the scope of this invention.

We claim:

1. A system for detecting the position of similar packets having a phosphorescent marking in the same predetermined location on each packet, comprising: a conveyor means for moving said packets in succession past first and second spaced stations, means for irradiating said phosphorescent markings on each packet at said first station to produce an afterglow from each of said markings, means for shielding said second station from said radiations including a tunnel through which said packets are passed, and separate photoelectric re sponsive means in different positions at said second station for detecting afterglow from said markings corresponding to different positions of said packets on said conveyor means.

2. A system according to claim 1 wherein said packets are postal packets and said markings thereon are on the postage stamps.

3. A system according to claim 1 wherein said conveyor means comprises a horizontal belt for supporting a row of said packets.

4. A system according to claim 3 wherein said means for irradiating comprises an ultraviolet light source.

5. A system according to claim 4 wherein said light source comprises a mercury vapor lamp.

6. A system according to claim 1 wherein said packets are postal letters and wherein there are four separate photoelectric responsive means at different positions at said second station.

7. A system according to claim 1 wherein said separate photoelectric means control a packet sorting device.

8. A system for detecting the position of similar postal packets having a phosphorescent stamp in a given location on each packet, comprising: a conveyor means for moving a regular series of said packets in succession past first and second spaced stations, means for irradiating said stamp on each packet at said first station to produce an afterglow from each stamp, a tunnel for said packets at said second station for excluding all light radiations from shining on said stamps, and separate photoelectric cells at difierent positions in said tunnel corresponding to the possible different positions of said packets for detecting said after glow and thereby to determine the position of said postal packets on said conveyor means for operating a subsequent postal packet facing machine.

9. A system according to claim 8 wherein said packets are letters and said system includes at least three separate photoelectric cells for three of the four possible positions of said letters on said conveyor means.

10. A system according to claim 8 wherein said packets 5 are letters and said system includes separate radiating means mounted on each side of said conveyor means at said first station for radiating the opposite sides of said letters.

References Cited in the file of this patent UNITED STATES PATENTS 1,217,092 Hopp Feb. 20, 1917 1,729,521 Roddy Sept. 24, 1929 2,609,928 Doust Sept. 9, 1952 2,704,634 Ranch Mar. 22, 1955 2,717,693 Holmes Sept. 13, 1955 FOREIGN PATENTS 656,873 Great Britain Sept. 5, 1951 675,556 Great Britain July 16, 1952 

